Conveyors of the articulated chain type for transporting products are known which comprise a mounting frame for supporting means which support and guide a conveyor belt which in turn comprises a plurality of plastic links constituting means for supporting the product and connected to each other in articulated fashion, each link having respective pluralities of longitudinal protrusions which extend in opposite longitudinal directions and which are transversally spaced from each other in such a way as to form respective spaces for receiving the longitudinal protrusions of an adjacent link.
More specifically, conveyors of the articulated chain type are known which are used for transporting products or objects along a respective path having straight stretches and curved stretches and which comprise a plurality of plastic links that are articulated to each other through respective pins inserted in transversal holes made in the longitudinal protrusions of the belt links.
For holding each connecting and articulation pin within the respectiver oblong hole in the belt link once the pin has been inserted to join respective links with each other, several solutions have been proposed.
One prior art solution contemplates the provision of a block separate from the plastic link to be associated, upon assembly, with a longitudinal protrusion lateral of the link in such a way as to close a hole at the end of the link through which the pin passes. A system of this kind for locking the articulation pin in the inserted condition is disadvantageous because it involves making separate parts and applying them to the link, which means complex and time-consuming assembly operations. Furthermore, once the separate blocks have been applied to the link, subsequent use leads to wear which may cause them to break and come apart from the link, allowing the articulation pin to slip out, with all the obvious problems that this evidently produces.
In another solution, a hole is made in one side of the link to allow the articulation pin to be inserted. The hole is, however, totally offset relative to the zone where the pin is inserted into the oblong holes in the longitudinal protrusions of the link. Inserting the pin thus means forcing the pin along a curved path so it goes into the lateral hole and from there into the oblong holes in the longitudinal protrusions which are in an offset position relative to the lateral hole. This task is complex and awkward and it is easy to break the link and/or the pin while it is being done.
Another common problem with conveyors of the articulated chain type is that the links, made of plastic, tend to break, especially at the lateral edges of the link which slide against the inside of the guide of the curved stretches of the belt. In effect, in the curved stretches, this sliding movement causes the link to scrape the inside guide surface, causing wear and subjecting the link to considerable stresses which lead not only to breakages but also to excessive vibrations and noise.
As means of centring and perpendicular retention, other prior art conveyor solutions contemplate the provision of perpendicular tabs terminating with transversal tabs suitable for gripping corresponding longitudinal guide profiles on the side opposite to the body of the link. In practice, these prior art conveyors use these L-shaped tabs as means of perpendicular retention and transversal centring for gripping respective first and second guide profiles at the bottom of the belt. With these conveyors, however, the result is excessive friction due to the multiplicity of the points of contact between the L-shaped tabs on the underside of the link and the corresponding guide profiles, which, in this case too, leads to excessive vibrations and noise.
Also known are conveyors which have transversally extending portions designed to be inserted into lateral dovetail guides in the form of transversal portions applied to the link bodies. The risk in this case is that stresses generated during conveyor operation tends to cause these applied portions to come out of the guides.
A yet further drawback of the prior art conveyors is due to the awkward and time-consuming process required to assemble current configurations of the guide means.